Has anyone done this BASIC water injection thing?

[ShadeTreeMech]

As was mentioned earlier, water injection was useful when pushing an engine to the limit and wanting to keep it there. The water would cool down that which was extremely hot and allow it to keep functioning.

For those of us trying to get from point a to point b, remember that a modern engine is watching the output from the o2 sensor to determine the fuel output and modify the injector cycles to compensate.

Using a fine mist of water (preferably washer fluid, as it is cheap and has a high alcohol content) the washer fluid will exit the exhaust as water and alcohol vapor, NOT as 02 and hydrogen. The water vapor shouldn't be recognized as o2, as it isn't o2 it is water vapor. This should cause the ECU to lean the mixture out, and since a cooling agent is in use, it should prevent damage to the engine from too hot of a combustion cycle.

Using enough water injection will likely decrease power in a naturally aspirated vehicle, but decrease in power = decrease in fuel usage.

[user removed]

What is not well understood (seems to me anyway) is that when you inject water into a combustion chamber, a significant amount of the heat energy of combustion is lost to expansion when it tries to turn the water into steam.

I have heard that the steam will help with expansion, but I doubt if you will see any benefit in pressure which is the driving force that creates power.

That might change if you preheated the water using exhaust gas then injected it into the combustion chamber as steam to become superheated steam when the fuel is ignited in the combustion chamber.

Not sure if you can get the pressures and heat necessary to get to a superheated steam condition, but it might be interesting to try it as an experiment.

regards
Mech

[tjts1]

If you have full authority over the air/fuel mixture, you can use water instead of extra fuel to reduce combustion temps at high load. Normally your engine will enrich the mixture from 14.7 afr (stoich) to something like 12.5-13 afr at full load (no manifold vacuum) in order to protect the engine. Under high load you could replace that extra fuel with water. You don't want water injection running all the time in the same way that you wouldn't want to run 12.5 afr at all times.

[IsaacCarlson]

Why not have a water jacket on the exhaust to boil water and inject steam? Keep the jacket small so the water would reach a decent boil. Feed it from a larger reservoir to keep it at a certain level. Would that work?

[mwebb]

02 sensors can not see 02
oxygen sensors can not detect oxygen

02 sensors detect combustibles
02 sensors detect combustibles
02 sensors detect combustibles
02 sensors detect combustibles
02 sensors detect combustibles

and
alcohol vapor will not exit the HOT exhaust
it will combust IN the exhaust if it has not already combusted in the combustion chamber .

liquid water will kill the 02 sensor deader than dog poop
liquid water will kill the 02 sensor deader than dog poop
liquid water will kill the 02 sensor deader than dog poop
liquid water will kill the 02 sensor (or AFR sensor) deader than dog poop
when it cracks the thimble because of temperature shock

Originally Posted by ShadeTreeMech

As was mentioned earlier, water injection was useful when pushing an engine to the limit and wanting to keep it there. The water would cool down that which was extremely hot and allow it to keep functioning.

For those of us trying to get from point a to point b, remember that a modern engine is watching the output from the o2 sensor to determine the fuel output and modify the injector cycles to compensate.

Using a fine mist of water (preferably washer fluid, as it is cheap and has a high alcohol content) the washer fluid will exit the exhaust as water and alcohol vapor, NOT as 02 and hydrogen. The water vapor shouldn't be recognized as o2, as it isn't o2 it is water vapor. This should cause the ECU to lean the mixture out, and since a cooling agent is in use, it should prevent damage to the engine from too hot of a combustion cycle.

Using enough water injection will likely decrease power in a naturally aspirated vehicle, but decrease in power = decrease in fuel usage.

[mwebb]

in my car
sucked into the intake , with a teeny little line made by creating an orifice with a red extension tube from an are-sol can
water injection decreases felt power and measured fuel economy

it does however clean the piston tops very well

[tjts1]

Originally Posted by mwebb

02 sensors can not see 02
oxygen sensors can not detect oxygen

02 sensors detect combustibles
02 sensors detect combustibles
02 sensors detect combustibles
02 sensors detect combustibles
02 sensors detect combustibles

Just because you can be obnoxious doesn't make you correct.

An oxygen sensor, or lambda sensor, is an electronic device that measures the proportion of oxygen (O2) in the gas or liquid being analyzed.

Oxygen sensor - Wikipedia, the free encyclopedia
Now read this.
How 5-Wire Sensors Work (Tech Edge)
Feel free to edit your comment at any time.

Originally Posted by mwebb

liquid water will kill the 02 sensor deader than dog poop
liquid water will kill the 02 sensor deader than dog poop
liquid water will kill the 02 sensor deader than dog poop
liquid water will kill the 02 sensor (or AFR sensor) deader than dog poop
when it cracks the thimble because of temperature shock [/COLOR]

So you're saying water that goes into the engine through the intake manifold, is compressed, exposed to combustion temperature and pressure, is going to pour out of the exhaust port as cold liquid and destroy the O2 sensor? You're a genius

[ConnClark]

I don't think water injection is going to have much effect on mileage unless your foot is in it all the time. The main reason is water injection doesn't work well at low loads. Its best use is an internal coolant and knock suppressor. It can also be utilized like a charge cooler to some degree to allow packing more fuel and air into the cylinder. In extremely high engine loads with very high temperatures it can cause the water molecule to disassociate act like a a catalyst to aid combustion.


The common conception that it will boil and expand and give a boost like a steam engine does not take into account that the energy to overcome the heat of vaporization is being taken from the combustion gasses and reducing their expansion. There is some gain from this but its not as much as you would think. Also to have an effect the water would have to enter the cylinder as a liquid and not a vapor.

[ShadeTreeMech]

I think water injection would be useful on an undersized-for-the job engine, ie putting a 2L engine into a Suburban with about 20 psi boost. It also would almost be a necessity if pushing a diesel to redline is a common occurance; water injection would bring down the exhaust gas temps very nicely.

But for cruising down the interstate, I kinda doubt it. But I do wonder what the effect having extra water vapor in the exhaust would be.

[mechman600]

If anyone has the means to add an extra direct injection and management system that can handle water, and increase the cam gear size so it is 3:1 to the crankshaft, and regrind the camshaft for 6-cycle operation we can have suck-squeeze-bang-blow-steam expansion-blow.
Six-stroke engine - Wikipedia, the free encyclopedia
It probably would have shown up by now if the EPA didn't frown upon the necessity of having to keep a water tank full on your car.